Payment Gateways that have processed a payment to use payment_status_id = 1

When a payment gateway processes a transaction successfully we have gone through a few ways of showing this
1) CiviCRM makes assumptions based on the 'type' of processor
2) Check is trxn_id is set iin the returned array
3) check if contribution_status_id is set to 1 in the returned array

Both 1 & 2 are heavily flawed in current usage.

3 is 'ok' but will quickly seem pretty odd when the payment is for part of the contribution & contribution_status_id = Completed

So, we have agreed 4.6 will support contribution_status_id AND payment_status_id from 4.6.5 and 4.7 will support payment_status_id only